1. Field of the Invention
The present invention relates to an accessory of a magnetic resonance imaging system, in particular to a magnetic resonance coil.
2. Description of the Prior Art
A magnetic resonance coil is used to receive a magnetic resonance signal of a body part to be examined in a magnetic resonance imaging device; said magnetic resonance signal is conveyed to an image reconstruction system to perform image reconstruction. The quality of an image reconstruction, which affects the diagnosis result, is an important factor, and the signal-to-noise ratio of the magnetic resonance signal, which determines the quality of the image reconstruction, is an important parameter. Generally, the higher the signal-to-noise ratio, the better the quality of the image reconstruction; and the smaller the distance between the magnetic resonance coil and the body part to be examined, the higher the signal-to-noise ratio.
Referring to FIG. 1, in a typical magnetic resonance coil 10 in prior art, an antenna portion 12 is formed inside a dashed line frame, the antenna portion 12 being formed by inductors and capacitors connected in series, and usually is in an annular shape and used for accommodating the body part to be examined inside it. A shortcoming of the magnetic resonance coil 10 is that said antenna portion 12 is a unity, the size of which is fixed. Therefore, the antenna portion 12 of the magnetic resonance coil 10 may not be suitable for the examination of different body parts to be examined. For example, in the case of the examined patient being too fat, the size of a body part to be examined being too large, or the body part to be examined being covered by thick plaster, etc., the antenna portion 12 may be not used because it is not able to accommodate the body part. In the case of the examined patient being too thin, the examined patient being a baby or a child, or the size of the body part to be examined being too small, although the antenna portion 12 can accommodate the body part, the distance between said portion 12 and the body part to be examined is large. This leads to a relatively low signal-to-noise for the received magnetic resonance signal, seriously affecting the quality of the reconstruction image, and can even lead in extreme cases to misdiagnosis.
In order to solve the above problems, in existing magnetic resonance systems, a large number of such magnetic resonance coils 10 with various sizes have to be provided for different cases, such as patients of different sizes, different patient body parts to be examined, and the adaptation for different situations so as to be suitable for the same body part to be examined of both an adult and a child. This results in a great increase in cost, and not only will the replacement of a magnetic resonance coil for different cases greatly increase the workload of a doctor, but also the necessary plug-pull or on-off power of the magnetic resonance system due to the frequent replacement of the magnetic resonance coils may lead to a shortened operating life of the magnetic resonance system, or more seriously lead to physical damage to the magnetic resonance system.
Chinese patent application No. 200520004982.8 discloses a receiving coil combination structure that is formed by interconnecting at least a rigid sub-component and at least a flexible sub-component, so as to produce a complex shape for the receiving coil to meet the detection needs of different body parts of a patient. However, during the application of this receiving coil, it is still necessary to increase, reduce or replace said rigid sub-component or flexible sub-component according to different cases, but it is not possible to freely adjust the size of the antenna portion. Therefore, inevitably the magnetic resonance system will frequently be plugged in and unplugged and have the power switched on and of, thereby resulting in a shortened operating life of the magnetic resonance system, or more seriously resulting in physical damage to the magnetic resonance system.